The present invention concerns crates for the transport of goods such as agricutural products, bottles and the like, and more particularly to crates provided with mutual interlocking means to safeguard against lateral sliding of one layer of crates relative to an underlying or overlying layer when the crates are piled in superimposed positions.
Piling of crates may be either in a fully overlapping relative position whereby the bottom of one overlying crate rests on, and is received by, the upper rim of an underlying crate, or in a partly overlapping fashion known in the art as "bonded brick-stacking".
In general, crates fall into two main categories, namely: solid crates and foldable crates. There have been accordingly developed over the years a large variety of separate solutions to satisfy the specific requirement posed by each of these categories--see, for example--U.S. Pat. No. 3,568,879 and U.K. Pat. No. 1,409,046 relating to solid crates, and U.S. Pat. No. 4,491,231 and Israel Design No. 12697 relating to foldable crates.
The problems, on the one hand, of stacking one-piece, integral crates, and on the other hand, of stacking foldable crates, have thus been more or less satisfactorily solved. However, due to their different design considerations, and resulting construction, attempts have hitherto not been made to adapt the two types of crates so that, as far as stacking is concerned, they would be compatible with each other. In other words, one is, at present, restricted to using one type of crate only and should one wish to use the other type of crate, it would have to be willing to undergo the expense and inconvenience of switching over to the other type of crate and to scrapping its existing stock of crates.
The solution to this problem is considerably more difficult than it appears at first sight, if one regards as a prerequisite the interlocking of the crates being secured by a suitable design applied to the bottom side only thereof - rather than in combination with the upper rim of the crate. This is due to the fact that the bottom wall of the foldable crate is separable from the four sides, being seated only by friction such that it inherently cannot bear any upwardly applied forces.